Johnsburg climate

Johnsburg Frost Dates and Growing Season

NOAA 1991-2020 normals for Mc Henry -Wg Stratton L&d, 7.9 km from Johnsburg, elevation 736 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mc Henry -Wg Stratton L&d. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around May 1 and the first fall freeze around October 11, a growing season of about 162 days.

Median at 36°F
last May 12, first October 1
Median at 32°F
last May 1, first October 11
Median at 28°F
last April 19, first October 22

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FMay 28May 24May 21May 17May 12May 9May 5May 2Apr 28
32°FMay 19May 13May 8May 4May 1Apr 28Apr 25Apr 21Apr 16
28°FMay 6Apr 30Apr 26Apr 22Apr 19Apr 16Apr 14Apr 10Apr 5
24°FApr 22Apr 18Apr 14Apr 10Apr 8Apr 5Apr 2Mar 30Mar 24
20°FApr 13Apr 6Apr 3Mar 31Mar 28Mar 25Mar 22Mar 17Mar 12
16°FApr 1Mar 28Mar 24Mar 20Mar 17Mar 14Mar 12Mar 8Mar 3

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FSep 19Sep 23Sep 26Sep 29Oct 1Oct 4Oct 7Oct 10Oct 14
32°FSep 27Oct 2Oct 5Oct 9Oct 11Oct 14Oct 17Oct 20Oct 24
28°FOct 7Oct 14Oct 17Oct 20Oct 22Oct 25Oct 28Oct 31Nov 4
24°FOct 21Oct 25Oct 28Oct 31Nov 2Nov 5Nov 8Nov 12Nov 17
20°FNov 1Nov 4Nov 8Nov 11Nov 14Nov 17Nov 21Nov 24Nov 28
16°FNov 8Nov 13Nov 18Nov 21Nov 24Nov 27Dec 1Dec 5Dec 12

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F160154149145141138132127120
32°F181175170166162158154149142
28°F204199193189185181177172165
24°F229222218213209205201195188
20°F254247242237232228223218211
16°F273266261256252247243238231

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
100% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
6,689
Cooling degree days, base 65°F
750
Growing degree days, base 40°F
4,971
Growing degree days, base 45°F
3,864
Growing degree days, base 50°F
2,891
Growing degree days, base 55°F
2,044
Growing degree days, base 60°F
1,327

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,34100
February1,10901
March902120
April525687
May23947294
June49156558
July9252708
August14200651
September12178411
October4349137
November788021
December1,15902

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 7.9 km from Johnsburg. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00115493 (Mc Henry -Wg Stratton L&d). Public domain.